Such a gas mask and breathing equipment is described in West German Patent No. DE-PS 20,88,41. In the prior-art device, the storage tank is surrounded by an air circulation duct on all sides, or the air circulation duct is designed in the form of tubes arranged within the storage tank. Ambient air, driven by natural convection, flows through the air circulation duct. A stopcock, by means of which the user is able to regulate the air flow and consequently the amount of respiration gas evaporated per unit of time, is provided at an air outlet arranged at the bottom.
It is disadvantageous in this prior-art gas mask and breathing equipment that the amount of air flowing as a result of convection is not sufficient, e.g., at low ambient temperatures, to deliver a sufficient amount of respiration gas, and that manual regulation requires too much attention on the part of the user.